When taxis charge anything other than the established authorized fares, you need to make it plain you will report them. Get their vehicle number (usually painted on their door and hood) as well as their affiliation (UTAAZ, APAAZ, UTZI, etc) which is also painted on their door along with the vehicle number. You can report them to their base office at 554-3680 as well as PROFECO (on Avenida Morelos near the intersection with Calle Vicente Guerrero next to ISSSTE).

You also mention you paid ".55 or .45 pesos" for a bus from La Ropa to el Centro. That can't be right, so would you please double check what amount they are charging you?